Synchronization solutions for distributed computing environments often deal with changes that occur on different computers. An update-delete conflict refers to a conflict arising, such as, during the synchronization of two devices, in which an entity is deleted on one device and the entity is updated on another device. For example, while away from the office, a user could delete on her personal digital assistant (PDA), a scheduled meeting, and the user's secretary could, on the user's desk top computer, add items to the agenda of the meeting. When the user returns to the office and synchronizes her PDA with her desktop, an update-delete conflict arises. Current attempted synchronization solutions include resolving the conflict in favor of the deletion. That is, the entity is deleted on both devices. Another solution treats the deletion as final and never detects or reports the conflict. Yet another attempted solution is to recreate a new entity which leads to problems such as duplicate entities.
An object of a typical synchronization system is to have all replicas converge to consistent versions. Convergence can be problematic when resolving update-delete conflicts. For example, in a distributed system having many devices, it is possible for one device to delete an entity and other devices to make independent changes to the entity. Current synchronization systems do not track the independent changes and ensure that all devices, including the device on which the entity was deleted, consistently converge.